1939 Chevy Truck Firewall Fabrication – No Recess!

Overcoming A Major Engine Setback With A Direct Sheetmetal Firewall

I can remember back when Total Cost Involved was about to drop the ’58 Chevy 235 engine and Gear Star Turbo 350 trans in my ’39 just as they finished up the suspension. Actually, what I recall the most was one very simple question they asked: “Do you want the firewall cut or not?” For those of you wondering why they’d even consider that, let me explain in a little more detail.

From day one, this project was always destined to retain an inline-six–but not the original 216 nor even an early 235 … it had to be of the ’56-62 variety, but the newer they get, the longer they get (from the water pump’s perspective). So, while the additional length can be overcome with a couple different methods–either the modified pumps offered by Patrick’s or the conversion kits to accept an early pump on a late motor–we thought it would be “cool” to stick with the factory equipment and squeeze `er in. To achieve a proper fit, TCI simply notched out the firewall “blister” enough for the back of the cylinder head and rocker cover. At the time, I never really put much further thought into it–patching the firewall was the least of my concerns back then.

As I got further along with the project (hanging the column, installing the intake/exhaust manifold, etc.), it started becoming quite clear that I would literally have my work “cut” out for me, as the seemingly simple sheetmetal patchwork was now looking more like a full fabrication job. Don’t get me wrong, it could and can be done, but I just wasn’t up for it, especially knowing that I could solve 90 percent of my problems (mostly labor and frustration) by just replacing the firewall altogether.

Fortunately, Direct Sheetmetal has patterns for not only ’37-39 Chevy pickup firewalls, but floorboard and transmission tunnel kits as well. The more I thought about it, this was definitely the way to go. Plus, unlike the task of fabricating practically an entirely new center portion for the stock one, installing a new firewall was something I had no doubts of being able to pull off without nearly as much effort, yet achieve the results I was after–fit and finish. As for the floors, I’m still up in the air regarding the direction I’ll go, but from the looks of it, I may end up integrating the Direct Sheetmetal toe boards and trans cover with the stock floor.

As usual, I went about this particular task a bit different than the instructions suggested–instead of fitting and welding the new firewall on the “outside” of the cowl, I trimmed it to fit from behind, just like the stock one. Ultimately, I wanted to retain as much of the original look as possible, and thus having the cowl flange still visible from the exterior would definitely help. This way, the DS firewall could be rosette-welded through the existing spot-weld holes; mounting from the outside requires a full perimeter weld. Either way you look at it, my major setback is now a thing of the past–now if I could just make up my mind and figure out just what I’m gonna do with the floor…

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